Floating dry dock



May 13, 1958 G C. ENGSTRAND FLOATING DRY DOCK Original Filed Dec. 7, 1950 2 Sheets-Sheet 1 INVENTOR. uizlzarafngstrazzd BY ATTORNEY May- 13, 1958 G. c. ENGSTRAND 2,334,311

FLOATING DRY DOCK Original Filed Dec. 7, 1950 '2 $heets-Sheet 2 INVENTOR. unmrafnysmzzd ATTORNEY United States Patent FLOATING DRY DOCK Gunnar C. Engstrand, New York, N. Y., assignor, by mesne assignments, to Frederic R. Harris, Inc., New York, N. Y., a corporation of New York Original application December 7, 1950, Serial No. 199,650, now Patent No. 2,740,367, dated April 3, 1956. Divided and this application February 16, 1955, Serial No. 488,504

3 Claims. (Cl. 114-45) This invention is an improvement in floating dry docks, comprising a pontoon, hull and side walls, and has for its chief object to provide a dock that may be easily managed and navigated to be floated through a water passage considerably narrower than the width of beam of the dock.

This application is a division of my application for patent on a floating dry dock, Serial No. 199,650, filed December 7, 1950, now United States Patent No. 2,740,367.

The invention of this application comprises a floating dry dock that may be tilted around its longitudinal axis to a position nearly vertical to its regular working position on an even keel. At such an angle, the dock will present a substantially reduced beam to a relatively narrow passageway such as the interior space of a canal lock; because the width of the dock is greater than the height of its side walls. The turning or tilting is accomplished by pumping water in and out, and the interior of the clock has different compartments that are built and arranged to be suitable for my purpose. The tilting may be expeditiously performed at any time with no special preparation whatever.

To this end, the dry dock is provided with a watertight bulkhead in each side wall, these bulkheads dividing the interior of the wing or side wall into separate compartments.

In this manner, I construct in each wing wall of the dock an upper compartment that will be flooded and a lower compartment that will at the same time be pumped out and lie at or beneath the plane of the outside water level when the dock is in its extreme tilted position. With the other wing wall and the hull between the sides also pumped out, the dock is then ready for canal passage.

The nature of the invention and the novel features thereof and their functions are fully described at length herein. My invention is especially adapted for the passage of military and naval docks through the Panama Canal, where the locks are only 110 feet wide while floating dry docks range up to 150 feet in width, as is required for the servicing of airplane carriers and other large vessels.

In the drawings:

Figure 1 shows a dock according to my invention sub merged, with the outline of a ship upon blocks in broken lines, included.

Figure 2 illustrates the first stage of the tilting operation which is, of course, executed with no ship in the dock.

Figure 3 shows the second phase, and

Figure 4 shows the dock in its final tilted-over position; and

Figures 5 and 6 are sectional details of modified forms of my invention.

The numeral 1 indicates the hull or pontoon of the dock, which has the wings or walls 2 on its top along the sides. When a ship is to be raised, the dock is sunk and the ship 3 is floated in to rest on the keel blocks 4. The hull is divided inside by two longitudinal upright bulkheads 5,

Patented May 13, 1958 2 the central flooding compartment 6. In each wing wall 2 is a sloping bulkhead 7, also extending from end to end the full length of the dock, and from the upper inner corner of the wall down towards the level of the deck 8 of the pontoon 1, ending at the outboard face of said wall 2.

The sloping bulkheads 7 are the means whereby the upper interior space of the wing walls 2 are divided from the remainder of the interior of the wing walls to make upper and lower compartments 10 and 11. Pipes 12 conmeet both compartments 11 to the compartments 6, running through buoyancy chambers 13 between the compartments 6 and 11, so that the water maybe pumped out from the entire dock from one side thereof. For security reasons, both the wing walls are equipped with the sloping bulkheads 7 so that if one side is damaged from any cause that side of the dock may be lifted out of the water with no loss of time. The pumping machinery, not shown, can be located in the buoyancy chambers 13, which are never flooded.

It is essential that the buoyancy chambers 13 be of such size that the weight of an equal volume of water is considerably in excess of the weight of the dock. To submerge it, the dock has to admit water to the compartments 6, 10 and 11; and to keep the dock on an even keel when servicing a ship, water must be pumped into both the walls 2 of the dock to the same level, all as shown in Figure 1.

To incline the dock, the one wing wall 2 must be empty; and part of the central compartment or chamber 6 and the lower or waterborne wing or wall 2 be partially pumped out, as illustrated in Figure 2. The buoyancy chambers 13 are located just inside the wing walls 2 in the pontoon 1 and the water-tight bulkheads 5 and inboard sides of the walls 2, which extend down to the bottom 9, form the sides thereof. Inside the buoyancy chambers the pumping machineryis located. These buoyancy chambers 13 are spaced apart so that there is a center pumping or flooding compartment 6 in the pontoon. Also the pipes 12 running through the buoyancy chambers permit water transfer from one side of the dock to the other. The necessary valves, pumps etc. are not shown on the drawings but will be of well known manufacture.

The next step is to evacuate the chamber 6 entirely of water and to pump out some of the water in the lower compartment 11 of the lowered or water-borne wall 2, as in Figure 3. To get the dock fully into position shown in Figure 4, the compartment 11 of the lower wing wall must be pumped out further and the upper chamber 10 of this wall must be nearly filled with water and the rest of the dock must be empty. When turned over to this degree, the dock is ready for transit through the relatively narrow passage 14.

It is understood that modifications may be made in the structural details of my floating dock without departing from the scope and spirit of my invention. The dock framework and outside plating of my dock are all of conventional design, and my invention resides in arrangement of the various bulkheads dividing the interior into compartments by which the results described above are obtained.

The clock, of course, has the necessary piping with inlet and outlet ports to fill and pump out the central compartment 6 and the upper compartments l0 and the lower compartments 11.

In the first stage of tilting, the dock is caused to list by the water that only partly fills the compartment 6 and the lower part of one compartment 11. The buoyant eifect of the unfilled compartment 6 and the lower compartment 13 are indicated by the arrows 15 and 16 respectively, and this is balanced by the effect of the water in the adjacent compartment 11, as indicated by the arrow 17 in Figure 2.

In the next stage, the compartment 6 is empty and some buoyancy is given to the lower part of the dock by the unfilled portion of the compartment 11 in the lowered wing. This buoyancy is offset by the presence of the Water in the two compartments of the same wing, as indicated by the arrows 18 and 19, see Figure 3.

When the dock attains the full tilted position illustrated in Figure 4, the weight of the water with the leverage represented by the distance between a vertical line through the arrow 19 and the center of gravity of the dock indicated at 21 is sufficient to balance the effective weight of the dock at whatever leverage exists on the opposite side of the point 21. Hence the dock is in stable equilibrium in the narrow passageway 14.

In Figure 5 the bulkhead 7a has a lower portion extending from within the wing wall down to the bottom of the deck and an upper horizontal portion 7b which extends to the outboard side of the wing wall; and in Figure 6 each wing wall has a horizontal bulkhead 7 b dividing the wing wall into upper and lower compartments 1% and 11b.

The over-all height of the wing walls of the dock is about 54 percent of the over-all width. The width or thickness of each wall is about 21 percent of the total height of the dock, and the thickness of each wall and the depth of the pontoon are about equal.

The volumes of the chambers and 13 are about equal and may be taken as one, the volume of the chamber 14 being slightly greater. The volume of the central chamber 6 can be taken as one and one-half and the volume of each chamber 11 as two.

Having described my invention what I believe to be new is:

1. A floating dry dock having a pontoon hull with bottom, a deck and wings at the sides of the hull, the height of each Wing being less than the beam of the dock, said hull having a central compartment and each wing having compartments closed against each other, all said compartments to be flooded and pumped out as required to sink and raise the dock, a bulkhead extending longitudinally along the interior of the Wing, one of said last-named compartments extending from the top of the wing containing it towards the deck of the pontoon, said one compartment having such capacity when flooded as to hold said Wing water-borne along its entire outboard side and the remainder of the dock above water in nearly vertical position, each bulkhead extending from the bottom adjacent the inboard side to the outboard side, above the deck, and being horizontal at the outboard side, said hull having buoyancy compartments, one extending along the hull between said middle compartment and each wing.

2. A floating dry dock having a pontoon hull with bottom, a deck and wings at the sides of the hull, the height of each wing being less than the beam of the dock, said hull having a central compartment and each wing having compartments closed against each other, all said compartments to be flooded and pumped out as required to sink and raise the dock, a bulkhead between said compartments in each wing, each bulkhead extending longitudinally along the interior of the wing, one of said last-named compartments extending from the top of the wing containing it towards the deck of the pontoon, said one compartment having such capacity when flooded as to hold said wing Water-borne along its entire outboard side and the remainder of the dock above water in nearly vertical position, each bulkhead extending upward at an incline from the bottom adjacent the inboard face of the wing toward the outboard face thereof, said hull having buoyancy compartments, one extending along the hull between said middle compartment and each wing.

3. A floating dry dock having a pontoon hull with bottom, a deck and wings at the sides of the hull, the height of each wing being less than the beam of the dock, said hull having a central compartment and each wing having two compartments closed against each other, all said compartments to be flooded and pumped out as required to sink and raise the dock, a bulkhead above the deck between said compartments in each Wing, each bulkhead extending longitudinally along the interior of the wing, one of said last-named compartments extending from the top of the wing containing it towards the deck of the pontoon, said one compartment having such capacity when flooded as to hold said wing water-borne along its entire outboard side and the remainder of the dock above water in nearly vertical position, each bulkhead extending horizontally across the wing from the inboard to the outboard face thereof, said hull having buoyancy compartments, one extending along the hull between said middle compartment and each wing.

References Cited in the file of this patent UNITED STATES PATENTS 755,854 Dieckhofl Mar. 29, 1904 1,486,257 Muller Mar. 11, 1924 2,576,928 Engstrand Dec. 4, 1951 2,740,367 Engstrand Apr. 3, 1956 FOREIGN PATENTS 393,111 Germany Apr. 4, 1924 

